The present invention relates to a utility steam generator with self-controlled pressure which is especially adapted to be used with little household electric appliances.
In the field of the little household electric appliances it is known a number of apparatus such as flat irons, cleaning devices of various kinds, and so on, requiring for their operation steam produced by a separate generator and using an electric resistance as a heat source.
These steam generators are generally filled manually at cold boiler, in such a way that, when the quantity of water initially loaded in the boiler is finished, it is first necessary to let the boiler cooling down and then to refill it with fresh water and await until water is heated and becomes steam.
This system has the risk to cause scaldings to the user when the latter, being in a hurry, as it often happens, tries to open the boiler to refill it before it has sufficiently cooled down.
Several devices were hither to proposed, consisting of valves and filling cups, but they do not solve the above mentioned problem, unless complex and expensive devices are used for this purpose.
The easiest solution indeed would be to add water by a micropump, already available on the market and used for instance on the coffee percolators, picking up water from an external reservoir, but to do as according to the state of the art it is necessary to provide the steam generator with several devices, namely a device controlling maximum and minimum water level, pressure switch, thermostat, in addition to the safety valve already provided on the known manually filled steam generators, but even such an obvious solution, being used in the steam generators of bigger size, does not give good results in such an application, because with these systems when fresh water is being added, a corresponding steam pressure decrease always occurs, so that it is often necessary to discontinue the use of the steam utilizing appliance.
As a matter of fact, in these little steam generators, the biggest difficulty consists in feeding the steam generator with such a little quantity of water as to cool the system without causing such an excessive decrease of the steam pressure, as to restrict or break steam flow.